# wx.Scrolled¶

The wx.Scrolled class manages scrolling for its client area, transforming the coordinates according to the scrollbar positions, and setting the scroll positions, thumb sizes and ranges according to the area in view.

There are two commonly used (but not the only possible!) specializations of this class:

• wx.ScrolledWindow, aka ScrolledPanel, is equivalent to wx.ScrolledWindow from earlier versions. Derived from wx.Panel, it shares wx.Panel’s behaviour with regard to TAB traversal and focus handling. Use this if the scrolled window will have child controls.

• wx.ScrolledCanvas, aka ScrolledWindow, derives from wx.Window and so doesn’t handle children specially. This is suitable e.g. for implementing scrollable controls such as tree or list controls.

Starting from version 2.4 of wxWidgets, there are several ways to use a wx.ScrolledWindow (and now wx.Scrolled). In particular, there are three ways to set the size of the scrolling area:

One way is to set the scrollbars directly using a call to SetScrollbars. This is the way it used to be in any previous version of wxWidgets and it will be kept for backwards compatibility.

An additional method of manual control, which requires a little less computation of your own, is to set the total size of the scrolling area by calling either wx.Window.SetVirtualSize , or wx.Window.FitInside , and setting the scrolling increments for it by calling SetScrollRate. Scrolling in some orientation is enabled by setting a non-zero increment for it.

The most automatic and newest way is to simply let sizers determine the scrolling area. This is now the default when you set an interior sizer into a wx.Scrolled with wx.Window.SetSizer . The scrolling area will be set to the size requested by the sizer and the scrollbars will be assigned for each orientation according to the need for them and the scrolling increment set by SetScrollRate. As above, scrolling is only enabled in orientations with a non-zero increment. You can influence the minimum size of the scrolled area controlled by a sizer by calling Window.SetVirtualSizeHints(). (Calling SetScrollbars has analogous effects in wxWidgets 2.4 – in later versions it may not continue to override the sizer.)

Note that if maximum size hints are still supported by Window.SetVirtualSizeHints(), use them at your own dire risk. They may or may not have been removed for 2.4, but it really only makes sense to set minimum size hints here. We should probably replace Window.SetVirtualSizeHints() with Window.SetMinVirtualSize() or similar and remove it entirely in future.

As with all windows, an application can draw onto a wx.Scrolled using a device context.

You have the option of handling the OnPaint handler or overriding the wx.Scrolled.OnDraw function, which is passed a pre-scrolled device context (prepared by wx.Scrolled.DoPrepareDC ).

If you don’t wish to calculate your own scrolling, you must call DoPrepareDC when not drawing from within OnDraw, to set the device origin for the device context according to the current scroll position.

A wx.Scrolled will normally scroll itself and therefore its child windows as well. It might however be desired to scroll a different window than itself: e.g. when designing a spreadsheet, you will normally only have to scroll the (usually white) cell area, whereas the (usually grey) label area will scroll very differently. For this special purpose, you can call SetTargetWindow which means that pressing the scrollbars will scroll a different window.

Note that the underlying system knows nothing about scrolling coordinates, so that all system functions (mouse events, expose events, refresh calls etc) as well as the position of subwindows are relative to the “physical” origin of the scrolled window. If the user insert a child window at position (10,10) and scrolls the window down 100 pixels (moving the child window out of the visible area), the child window will report a position of (10,-90).

## Window Styles¶

This class supports the following styles:

• wx.HSCROLL: If this style is specified and VSCROLL isn’t, the window will be scrollable only in horizontal direction (by default, i.e. if neither this style nor VSCROLL is specified, it scrolls in both directions).

• wx.VSCROLL: If this style is specified and HSCROLL isn’t, the window will be scrollable only in vertical direction (by default, i.e. if neither this style nor HSCROLL is specified, it scrolls in both directions).

• wx.ALWAYS_SHOW_SB: Since wxWidgets 2.9.5, specifying this style makes the window always show its scrollbars, even if they are not used. See ShowScrollbars.

• wx.RETAINED: Uses a backing pixmap to speed refreshes. Motif only.

## Events Emitted by this Class¶

Handlers bound for the following event types will receive a wx.ScrollWinEvent parameter.

• EVT_SCROLLWIN: Process all scroll events.

• EVT_SCROLLWIN_TOP: Process wxEVT_SCROLLWIN_TOP scroll-to-top events.

• EVT_SCROLLWIN_BOTTOM: Process wxEVT_SCROLLWIN_BOTTOM scroll-to-bottom events.

• EVT_SCROLLWIN_LINEUP: Process wxEVT_SCROLLWIN_LINEUP line up events.

• EVT_SCROLLWIN_LINEDOWN: Process wxEVT_SCROLLWIN_LINEDOWN line down events.

• EVT_SCROLLWIN_PAGEUP: Process wxEVT_SCROLLWIN_PAGEUP page up events.

• EVT_SCROLLWIN_PAGEDOWN: Process wxEVT_SCROLLWIN_PAGEDOWN page down events.

• EVT_SCROLLWIN_THUMBTRACK: Process wxEVT_SCROLLWIN_THUMBTRACK thumbtrack events (frequent events sent as the user drags the thumbtrack).

• EVT_SCROLLWIN_THUMBRELEASE: Process wxEVT_SCROLLWIN_THUMBRELEASE thumb release events.

New in version 2.9.0: The wx.Scrolled template exists since version 2.9.0. In older versions, only wx.ScrolledWindow (equivalent of ScrolledPanel) was available.

Note

Use wx.Scrolled for applications where the user scrolls by a fixed amount, and where a ‘page’ can be interpreted to be the current visible portion of the window. For more sophisticated applications, use the wx.Scrolled implementation as a guide to build your own scroll behaviour or use wx.VScrolledWindow or its variants.

Note

See wx.Scrolled.Create if you want to use wx.Scrolled with a custom class.

Note

Don’t confuse ScrollWinEvents generated by this class with wx.ScrollEvent objects generated by wx.ScrollBar and wx.Slider.

Todo

review docs for this class replacing SetVirtualSizeHints() with SetMinClientSize().

## Class Hierarchy¶

Inheritance diagram for class Scrolled:

## Methods Summary¶

 __init__ Default constructor. AdjustScrollbars CalcScrolledPosition Translates the logical coordinates to the device ones. CalcUnscrolledPosition Translates the device coordinates to the logical ones. Create Creates the window for two-step construction. DisableKeyboardScrolling Disable use of keyboard keys for scrolling. DoPrepareDC Call this function to prepare the device context for drawing a scrolled image. EnableScrolling Enable or disable use of wx.Window.ScrollWindow for scrolling. GetClassDefaultAttributes GetScaleX GetScaleY GetScrollLines GetScrollPageSize GetScrollPixelsPerUnit Get the number of pixels per scroll unit (line), in each direction, as set by SetScrollbars . GetSizeAvailableForScrollTarget Function which must be overridden to implement the size available for the scroll target for the given size of the main window. GetTargetRect GetTargetWindow GetViewStart Get the position at which the visible portion of the window starts. IsAutoScrolling Are we generating the autoscroll events? IsRetained Motif only: True if the window has a backing bitmap. OnDraw Called by the default paint event handler to allow the application to define painting behaviour without having to worry about calling DoPrepareDC . PrepareDC This function is for backwards compatibility only and simply calls DoPrepareDC now. Scroll Scrolls a window so the view start is at the given point. SendAutoScrollEvents This method can be overridden in a derived class to forbid sending the auto scroll events - note that unlike StopAutoScrolling it doesn’t stop the timer, so it will be called repeatedly and will typically return different values depending on the current mouse position. SetScale SetScrollPageSize SetScrollRate Set the horizontal and vertical scrolling increment only. SetScrollbars Sets up vertical and/or horizontal scrollbars. SetTargetRect SetTargetWindow Call this function to tell wx.Scrolled to perform the actual scrolling on a different window (and not on itself). ShouldScrollToChildOnFocus This method can be overridden in a derived class to prevent scrolling the child window into view automatically when it gets focus. ShowScrollbars Set the scrollbar visibility. StopAutoScrolling Stop generating the scroll events when mouse is held outside the window.

## Class API¶

class wx.Scrolled(T)

Possible constructors:

Scrolled()

Scrolled(parent, id=-1, pos=DefaultPosition, size=DefaultSize,
style=HSCROLL|VSCROLL, name="scrolledWindow")


The Scrolled class manages scrolling for its client area, transforming the coordinates according to the scrollbar positions, and setting the scroll positions, thumb sizes and ranges according to the area in view.

### Methods¶

__init__(self, *args, **kw)

__init__ (self)

Default constructor.

__init__ (self, parent, id=-1, pos=DefaultPosition, size=DefaultSize, style=HSCROLL|VSCROLL, name=”scrolledWindow”)

Constructor.

Parameters
• parent (wx.Window) – Parent window.

• id (wx.WindowID) – Window identifier. The value ID_ANY indicates a default value.

• pos (wx.Point) – Window position. If a position of wx.DefaultPosition is specified then a default position is chosen.

• size (wx.Size) – Window size. If a size of wx.DefaultSize is specified then the window is sized appropriately.

• style (long) – Window style. See wx.Scrolled.

• name (string) – Window name.

Note

The window is initially created without visible scrollbars. Call SetScrollbars to specify how big the virtual window size should be.

AdjustScrollbars(self)

CalcScrolledPosition(self, *args, **kw)

CalcScrolledPosition (self, x, y)

Translates the logical coordinates to the device ones.

For example, if a window is scrolled 10 pixels to the bottom, the device coordinates of the origin are (0, 0) (as always), but the logical coordinates are (0, 10) and so the call to CalcScrolledPosition(0, 10, xx, yy) will return 0 in yy.

CalcScrolledPosition (self, pt)

Parameters

pt (wx.Point) –

Return type

wx.Point

CalcUnscrolledPosition(self, *args, **kw)

CalcUnscrolledPosition (self, x, y)

Translates the device coordinates to the logical ones.

For example, if a window is scrolled 10 pixels to the bottom, the device coordinates of the origin are (0, 0) (as always), but the logical coordinates are (0, 10) and so the call to CalcUnscrolledPosition(0, 0, xx, yy) will return 10 in yy.

CalcUnscrolledPosition (self, pt)

Parameters

pt (wx.Point) –

Return type

wx.Point

Create(self, parent, id=-1, pos=DefaultPosition, size=DefaultSize, style=HSCROLL|VSCROLL, name="scrolledWindow")

Creates the window for two-step construction.

Derived classes should call or replace this function. If it is not replaced, bear in mind that it calls T.Create() through the global function CreateScrolled so if T.Create() has a different signature than wx.Scrolled.Create you should implement overloaded CreateScrolled which would call T.Create() in the correct manner.

Parameters
Return type

bool

Scrolled.__init__ and CreateScrolled for details.

DisableKeyboardScrolling(self)

Disable use of keyboard keys for scrolling.

By default cursor movement keys (including Home, End, Page Up and Down) are used to scroll the window appropriately. If the derived class uses these keys for something else, e.g. changing the currently selected item, this function can be used to disable this behaviour as it’s not only not necessary then but can actually be actively harmful if another object forwards a keyboard event corresponding to one of the above keys to us using ProcessWindowEvent() because the event will always be processed which can be undesirable.

New in version 2.9.1.

DoPrepareDC(self, dc)

Call this function to prepare the device context for drawing a scrolled image.

It sets the device origin according to the current scroll position. DoPrepareDC is called automatically within the default wxEVT_PAINT event handler, so your OnDraw override will be passed an already ‘pre-scrolled’ device context. However, if you wish to draw from outside of OnDraw (e.g. from your own wxEVT_PAINT handler), you must call this function yourself.

For example:

def OnEvent(self, event):

dc = wx.ClientDC(self)
self.DoPrepareDC(dc)

dc.SetPen(wx.BLACK_PEN)

x, y = event.GetPosition()

if (xpos > -1 and ypos > -1 and event.Dragging()):
dc.DrawLine(xpos, ypos, x, y)

xpos = x
ypos = y


Notice that the function sets the origin by moving it relatively to the current origin position, so you shouldn’t change the origin before calling DoPrepareDC or, if you do, reset it to (0, 0) later. If you call DoPrepareDC immediately after device context creation, as in the example above, this problem doesn’t arise, of course, so it is customary to do it like this.

Parameters

dc (wx.DC) –

EnableScrolling(self, xScrolling, yScrolling)

Enable or disable use of wx.Window.ScrollWindow for scrolling.

By default, when a scrolled window is logically scrolled, wx.Window.ScrollWindow is called on the underlying window which scrolls the window contents and only invalidates the part of the window newly brought into view. If False is passed as an argument, then this “physical scrolling” is disabled and the window is entirely invalidated whenever it is scrolled by calling wx.Window.Refresh .

It should be rarely necessary to disable physical scrolling, so this method shouldn’t be called in normal circumstances.

Parameters
• xScrolling (bool) – If True, enables physical scrolling in the x direction.

• yScrolling (bool) – If True, enables physical scrolling in the y direction.

static GetClassDefaultAttributes(variant=WINDOW_VARIANT_NORMAL)
Parameters

variant (WindowVariant) –

Return type

wx.VisualAttributes

GetScaleX(self)
Return type

float

GetScaleY(self)
Return type

float

GetScrollLines(self, orient)
Parameters

orient (int) –

Return type

int

GetScrollPageSize(self, orient)
Parameters

orient (int) –

Return type

int

GetScrollPixelsPerUnit(self)

Get the number of pixels per scroll unit (line), in each direction, as set by SetScrollbars .

A value of zero indicates no scrolling in that direction.

Return type

tuple

GetSizeAvailableForScrollTarget(self, size)

Function which must be overridden to implement the size available for the scroll target for the given size of the main window.

This method must be overridden if SetTargetWindow is used (it is never called otherwise). The implementation should decrease the size to account for the size of the non-scrollable parts of the main window and return only the size available for the scrollable window itself. E.g. in the example given in SetTargetWindow documentation the function would subtract the height of the header window from the vertical component of size.

Parameters

size (wx.Size) –

Return type

wx.Size

GetTargetRect(self)
Return type

wx.Rect

GetTargetWindow(self)
Return type

wx.Window

GetViewStart(self)

Get the position at which the visible portion of the window starts.

Return type

tuple

IsAutoScrolling(self)

Are we generating the autoscroll events?

Return type

bool

IsRetained(self)

Motif only: True if the window has a backing bitmap.

Return type

bool

OnDraw(self, dc)

Called by the default paint event handler to allow the application to define painting behaviour without having to worry about calling DoPrepareDC .

Instead of overriding this function you may also just process the paint event in the derived class as usual, but then you will have to call DoPrepareDC yourself.

Parameters

dc (wx.DC) –

PrepareDC(self, dc)

This function is for backwards compatibility only and simply calls DoPrepareDC now.

Notice that it is not called by the default paint event handle ( DoPrepareDC is), so overriding this method in your derived class is useless.

Parameters

dc (wx.DC) –

Scroll(self, *args, **kw)

Scroll (self, x, y)

Scrolls a window so the view start is at the given point.

Parameters
• x (int) – The x position to scroll to, in scroll units.

• y (int) – The y position to scroll to, in scroll units.

Note

The positions are in scroll units, not pixels, so to convert to pixels you will have to multiply by the number of pixels per scroll increment. If either parameter is wx.DefaultCoord (-1), that position will be ignored (no change in that direction).

Scroll (self, pt)

This is an overload of Scroll ; see that function for more info.

Parameters

pt (wx.Point) –

SendAutoScrollEvents(self, event)

This method can be overridden in a derived class to forbid sending the auto scroll events - note that unlike StopAutoScrolling it doesn’t stop the timer, so it will be called repeatedly and will typically return different values depending on the current mouse position.

The base class version just returns True.

Parameters

event (wx.ScrollWinEvent) –

Return type

bool

SetScale(self, xs, ys)
Parameters
• xs (float) –

• ys (float) –

SetScrollPageSize(self, orient, pageSize)
Parameters
• orient (int) –

• pageSize (int) –

SetScrollRate(self, xstep, ystep)

Set the horizontal and vertical scrolling increment only.

See the pixelsPerUnit parameter in SetScrollbars .

Parameters
• xstep (int) –

• ystep (int) –

SetScrollbars(self, pixelsPerUnitX, pixelsPerUnitY, noUnitsX, noUnitsY, xPos=0, yPos=0, noRefresh=False)

Sets up vertical and/or horizontal scrollbars.

The first pair of parameters give the number of pixels per ‘scroll step’, i.e. amount moved when the up or down scroll arrows are pressed. The second pair gives the length of scrollbar in scroll steps, which sets the size of the virtual window.

xPos and yPos optionally specify a position to scroll to immediately.

For example, the following gives a window horizontal and vertical scrollbars with 20 pixels per scroll step, and a size of 50 steps (1000 pixels) in each direction:

window.SetScrollbars(20, 20, 50, 50)


wx.Scrolled manages the page size itself, using the current client window size as the page size.

Note that for more sophisticated scrolling applications, for example where scroll steps may be variable according to the position in the document, it will be necessary to derive a new class from wx.Window, overriding OnSize() and adjusting the scrollbars appropriately.

Parameters
• pixelsPerUnitX (int) – Pixels per scroll unit in the horizontal direction.

• pixelsPerUnitY (int) – Pixels per scroll unit in the vertical direction.

• noUnitsX (int) – Number of units in the horizontal direction.

• noUnitsY (int) – Number of units in the vertical direction.

• xPos (int) – Position to initialize the scrollbars in the horizontal direction, in scroll units.

• yPos (int) – Position to initialize the scrollbars in the vertical direction, in scroll units.

• noRefresh (bool) – Will not refresh window if True.

SetTargetRect(self, rect)
Parameters

rect (wx.Rect) –

SetTargetWindow(self, window)

Call this function to tell wx.Scrolled to perform the actual scrolling on a different window (and not on itself).

This method is useful when only a part of the window should be scrolled. A typical example is a control consisting of a fixed header and the scrollable contents window: the scrollbars are attached to the main window itself, hence it, and not the contents window must be derived from wx.Scrolled, but only the contents window scrolls when the scrollbars are used. To implement such setup, you need to call this method with the contents window as argument.

Notice that if this method is used, GetSizeAvailableForScrollTarget method must be overridden.

Parameters

window (wx.Window) –

ShouldScrollToChildOnFocus(self, child)

This method can be overridden in a derived class to prevent scrolling the child window into view automatically when it gets focus.

The default behaviour is to scroll this window to show its currently focused child automatically, to ensure that the user can interact with it. This is usually helpful, but can be undesirable for some windows, in which case this method can be overridden to return False for them to prevent any scrolling from taking place when such windows get focus.

Parameters

child (wx.Window) –

Return type

bool

New in version 4.1/wxWidgets-3.1.3.

ShowScrollbars(self, horz, vert)

Set the scrollbar visibility.

By default the scrollbar in the corresponding direction is only shown if it is needed, i.e. if the virtual size of the scrolled window in this direction is greater than the current physical window size. Using this function the scrollbar visibility can be changed to be:

• wx.SHOW_SB_ALWAYS: To always show the scrollbar, even if it is not needed currently (wxwx.ALWAYS_SHOW_SB style can be used during the window creation to achieve the same effect but it applies in both directions).

• wx.SHOW_SB_NEVER: To never show the scrollbar at all. In this case the program should presumably provide some other way for the user to scroll the window.

• wx.SHOW_SB_DEFAULT: To restore the default behaviour described above.

Note that the window must be created before calling this method.

Parameters

New in version 2.9.0.

StopAutoScrolling(self)

Stop generating the scroll events when mouse is held outside the window.

### Properties¶

ScaleX

ScaleY

TargetRect

TargetWindow